There once was a moth
That lived on a sloth
All snuggled in tight in its hair
But it's small fry eat crap
So to avoid a food trap
Moths have to lay all their eggs...down there.

(Oh sure, they're clean now, but just wait til you see the s**t-eating moths they bring home)

Waage and Montgomery. "Cryptoses choloepi: A Coprophagous Moth That Lives on a Sloth" Science, 1976.

Ah. Coprophagy. It may sound like a weird fetish, but in fact the consumption of crap (and I don't mean fast food) can provide a lot of nutrition. Many species, like sloths, for example, eat a lot of plant matter. Plants are pretty tough to digest, and some of the nutrition is just going to go right through you. Some animals, like rabbits, reduce, reuse, and recycle, by eating their own poop. But sloths have different priorities.

Sloths are slow. When they are hanging almost motionless in the trees, camouflaged by the algae that live in their fur to blend in with the leaves, they are relatively safe from predators. There is little movement to detect, and then of course, if you're going to eat it, you often have to go out on a limb, so to speak.

But there is one time when sloths are more vulnerable. When they poop.

And who can blame them? Aren't we all a little vulnerable when dropping some kids off at the pool? But sloths are more than a little vulnerable. They climb down from the trees to the ground to do the business. They hang on to a lower branch, dig a hole with their hind feet, poop delicately in their homemade latrine, and then cover it up with leaves, to hide the smell from potential predators.

It all seems pretty complex for something that doesn't move at all for up to 10 hours per day. But it's a golden opportunity for a moth.

This is Crptoses choloepi, the moth in question. It can fly, but in its adult stage, it mostly hangs out on sloths. So much so that on any given sloth you can find between 20 to 130 moths. It's not quite certain (at least, from this paper) what they eat, but they spend a lot of time in the fur of the sloth, and the authors think they might dine on the skin secretions of the sloth.

But those are the adults. When they need to spread their genes around, where do they go? What do they do? If they lay eggs ON the sloth, it's never been found. No, instead, as these authors found, the moth babies like themselves some sloth s**t.

How did the authors find this out? A baby moth buffet, of course. They collected a whole bunch of pregnant female moths off sloths, and got them to lay their eggs on a surface. They then laid out for the moth larvae a smorgasboard of potential mothy foods: sloth hair, sloth skin, the leaves that sloth normally eat, and of course...sloth poop. Despite the potential delicious flavors of sloth hair, the lavae went right for the sloth poop.

Based on this behavior, the author hypothesize that male and female moths congregate on sloths. There, they mate, and then the the pregnant females detach from the sloth when the sloth makes it's weekly trip to the forest floor for all its pooping needs. The larvae end up on the sloth poop, nicely buried by leaves, protected, and surrounded by piles of delicious crap, where they can mature in safety. When they are finally adults, they can fly back up into the trees, to find another sloth, and continue the circle of life.

The pictures there aren't very good, but if you look closely you can see the moth on the left, on the sloth's knee, and on the right a whole collection of moths on the sloth's butt, all ready and in position.

It makes me wonder, are there microscopic organisms we haven't yet found, not moths perhaps, but maybe some other organism, that lives on us and NEEDS us, needs our poop? Have we possibly eradicated a whole species due to the development of the toilet?! Will we never know the potential for our own crap eating companions? Science may someday, I hope, tell us the answer.

Today's Friday Weird Science barely came through, friends. My computer has up and gone kaput, and I'm on an old creaky machine that's a backup. Everyone please sacrifice to the technological gods for the safety of my MacBook Shotput. Meanwhile, I'm praising Dropbox and external harddrives. Security issues, yes. But I still have my stuff.

Nice! Very ..um...refreshing Friday weird science poste. To be fair I will try to place that nugget of information in a conversation as soon as possible (who doesn't like talking about sloths? Or poop for that matter!). Thanks for the random general knowledge.

[…] algae, and moths in the genus Cryptoses. It’s been known for a long time that Cryptoses moths lay their eggs in sloth dung, and that their larvae eat it. As adults, the moths seek out a sloth, and settle into its fur to […]